Abstract:
The effects of Zinc Oxide (ZnO) and
E. Coli
-derived 6-phytase supplemented-diet on
the reproductive performance in aged broiler breede
r hens and on immune responses of
their progeny chicks were studied. In a 2×4 factori
al arrangement, 2 inclusion levels (0 or
300 U kg
-1
diet) of
E. coli
-derived phytase and 4 inclusion levels (30, 60, 90
, and 120 mg
kg-
1
diet) of ZnO were provided from 62 throughout 72 w
eeks of age. A total of 128 hens
were randomly assigned into 8 dietary treatments wi
th 4 replicates of 4 hens each. During
66 to 71 weeks of age, egg production and egg weigh
ts were daily recorded. Results
showed that ZnO and ZnO×phytase interaction affecte
d the egg weight and fertility rate
(P< 0.01). Adding ZnO and phytase to diet increased
the relative weight of bursa of
Fabricius and liver in the hatchlings. Also, the in
teractive effect of ZnO and phytase on
the relative weight of heart was significantly affe
cted by the hatchlings (P< 0.01). In
conclusion, dietary supplementation of ZnO and
E. coli
-derived 6-phytase profoundly
improved the fertility rate in aged broilers breede
r hens, although the effects on immunity
of their progeny were negligible.
Keywords:
Aging, Dietary supplementation, Hatchability, Late
production, Reproduction.
